[Novalug] Ubuntu installation versions (was: Recommendations for reading/self-learning - > Virtual Infrastructure and Cisco)

Dave K novalug@soupy.org
Wed Jan 30 17:20:28 EST 2013


Hi Ed:

On Wed, Jan 30, 2013 at 05:07:16PM -0500, Ed James wrote:
> Greg,
> 
>    Generally when I add a disk to a machine, it's an older disk with "stuff"
> on it, and the machine itself has a newer drive with a recent/fresh install.
> All I want to do is mount the old drive onto the new dir system somewhere.
> Or, if the old drive is a USB flashdrive, let the system "mount" it under
> /media for me.
> 
>   Google on: adding new drive to lvm
> 
> and you'll find instructions that are not quite so simple.  Granted, there might
> actually be a really simple way to do what I want, which would involve
> mounting (somehow) an older drive that never was part of an LVM system
> onto an LVM system.  However, every thing I found had several extra
> steps involved.  Each step has a risk that I'd mess up something somehow
> somewhere sometime.  So I'm finding extra risk, extra complexity, but
> no reason why I should use the new way.  The older way works fine, has
> never caused a problem.

I'd advocate mounting the older drive under a place like /media, copying
its contents, then simply running vgextend vg_myvolgroup /dev/newdrive
to add the disk to LVM.

> And the flip side is, I'm not sure what happens under LVM when I remove
> a drive.  My current system, I just unplug it.

If you're not spanning a volume group across multiple physical disks,
there's no issue.  If you had / on an LV that was part of a VG that
spanned physical disks, you wouldn't want to unplug things unless you
knew what you were doing.

You can do what I do, which is to have a VG that's for internal drives,
and a different VG for external/removable drives.  

> I'm still willing to be convinced to move to LVM, but I really need a concrete
> reason to do so.  Perhaps my environment doesn't provide any such need
> at this point in time.

I like LVM because it's really flexible, allows easy snapshots, can
combine LV + file system resizes, and permits easy expansion and migration.  

I currently have a 2T volume on external drives.  When I'm ready to
expand it, I'll simply add bigger drives to the volume group and then
evict the smaller drives.  Trivial with LVM.

Best regards,
-A. Dave



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